反应详情

温度

0 °C

O-Benzyl-D-threonine (0.92 g, 4.4 mmole) (prepared by the method of T. Mizoguchi, G. Levin, D. W. Woolley, and J. M. Stewart, J. Org. Chem., 1968, 33, 903, who described the L-isomer) was suspended in water (20 ml) and the pH adjusted to 9.5 , giving a virtually complete solution. This was cooled to 0° C. and stirred while 4-ethyl-2,3-dioxopiperazine-1-carbonyl chloride (1.00 g, 4.9 m mole) in AR acetone (10 ml) was added dropwise. The pH was kept at 9.5 by the addition of further base while the solution was allowed to regain room temperature. After 2 h the solution was acidified to pH 2 and the bulk of the acetone removed by evaporation. The oily product was extracted into ethyl acetate (3×50 ml), then the total organic phase was washed once with brine and dried over sodium sulphate. Evaporation gave the title acid (1.36 g, 82%) as a colourless non-crystalline foam which retained solvent traces tenaciously; Rf 0.35 in chloroform:methanol:acetic acid, 17:2:1; δ(CDCl3) 0.75-1.35 (5H, m, CH3CH and NCH2CH3), 3.1-3.7 (4H, m, 2 NCH2), 3.9-4.25 (2H, m, NCH2), 4.50 (2H, m, CH--CH), 6.25 (1H, brs, D2O exch, OH), 7.25 (5H, s, aryl), 9.50 (1H, brd), J 7 Hz, D2O exch, NH), 9.70 (1H, brs, D2O exch, CO2H).

1. customgiving a virtually complete solution
2. additionwas added dropwise
3. additionThe pH was kept at 9.5 by the addition of further base while the solution
4. customto regain room temperature
5. customthe bulk of the acetone removed by evaporation
6. extractionThe oily product was extracted into ethyl acetate (3×50 ml)
7. washthe total organic phase was washed once with brine
8. dry with materialdried over sodium sulphate
9. customEvaporation
10. customgave the title acid (1.36 g, 82%) as a colourless non-crystalline foam which